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HANDBOOK OF PHYSIOLOGY. 



the fissure of Sylvius, and joins the superior temporal convolution, and 

 a posterior part (b) (angular gyrus) which hooks round into the middle 

 temporal convolution. 



3. Temporo-sphenoidal (T.), contains three well-marked convolutions, 

 parallel to each other, termed the superior, middle, and inferior temporal. 

 The superior and middle are separated by the parallel fissure. 



4. Occipital (0.). This lobe lies behind the external perpendicular 

 or parieto-occipital fissure, and contains three convolutions, termed the 

 superior, middle, and inferior occipital. They are often not well 

 marked. In man, the external parieto-occipital fissure is only to be dis- 

 tinguished as a notch in the inner edge of the hemisphere; below this it 

 is quite obliterated by the four annectent gyri (plis de passage) which 



P 



FIG. 341. Lateral view of the brain ^semi-diagrammatic^. F, Frontal lobe; P, Parietal lobe; O, Oc- 

 - ' " ascending ramus 



arietal 

 erior 



, , , , . , 



frontal sulcus; f 3, praecentral sulcus; PI. superior parietal lobule; P2, inferior parietal lobule con- 

 sisting of P2, supramarginal gyrus, and P2', angular gyrus; ip, interparietal sulcus; cm, termination 

 of callosa-marginal fissure; Ol, first, O2. second, O3. third occipital convolutions; po, parieto-occip 

 ital fissure: o, transverse occipital fissure; o2, sulcus occipitalis inferior; Tl, first, T2, second, T3, 

 third temporo-sphenoidal convolutions; tl, first, t2, second temporo-sphenoidal fissures. (Ecker.) 



run nearly horizontally. The upper two connect the parietal, and the 

 lower two the temporal with the occipital lobe. 



5. Central lobe, or island of Eeil, which contains a number of radi- 

 ating convolutions (gyri operti). 



When the cerebral hemispheres have been removed by transverse cuts 

 at a level of the corpus callosum, and that body has been cut through on 

 either side about half an inch from the middle line by an antero-poste- 

 rior vertical incision, a considerable space on either side of the middle 



